Cardiac development is a complex process regulated in part by the combinatorial interactions of multiple transcriptional regulators, many of which have been identified over the last decade. Fine control of the level of these regulators is critical for normal heart development. MicroRNAs (miRNAs) are small RNA molecules capable of mediating this fine control by binding to mRNA targets and inhibiting message translation. First described in C. elegans, miRNAs have subsequently been identified in vertebrates with over 300 miRNAs now described in humans. Further, there are a growing number of examples of miRNAs regulating distinct processes in vertebrate development, including heart development. Our preliminary results suggest that one particular miRNA, miR-130a, targets a key transcriptional regulator of cardiac development, FOG-2. Given the importance of FOG-2 for cardiac development, we hypothesize that the levels of miR-130a may also be important for normal heart formation. As an initial approach to test this hypothesis, we propose the following aims: Specific Aim 1. Determine the pattern of miR-130a expression in the developing embryo. Hypothesis: MicroRNA130a will be expressed in a tissue and/or temporally restricted pattern during cardiac development. A. Define the temporal pattern of miR-130a expression in the embryonic heart using northern analysis. B. Define the spatial pattern of miR130a expression in the mouse embryo using in situ hybridization. Specific Aim 2. Determine the alteration of miR-130a target protein expression in vitro using adenoviral-mediated miR-130a over-expression in cultured cardiocytes. Hypothesis: Over-expression of miR-130a will lead to decreased protein levels of miR-130a targets. A. Generate a recombinant adenovirus capable of programming expression of miR-130a. B. Infect primary neonatal cardiocytes in vitro and assay for alterations in miR-130a target gene expression. Given the burden of congenital heart disease, it is important to identify the regulators in the process of heart development. With the emerging understanding of microRNAs in the regulation of gene expression, its role, not only in congenital heart disease, merits further investigation. MicroRNA-130a, through its potential interaction with FOG-2, may play a significant role in normal heart development. [unreadable] [unreadable] [unreadable]